They cite the first unequivocal evidence that a duckbill dinosaur managed to escape from one of these ancient top predators. The tale is written on the duckbill's fossilized skin and skull.

Resembling an alligator's hide, the skin was discovered next to the skull, which carries healed bone scars from bites, say paleontologists Bruce Rothschild of the University of Kansas in Lawrence and Robert Depalma of the Palm Beach Museum of Natural History in Fort Lauderdale. "The spacing of large tooth drags on the skull bones is consistent with a very large tyrannosaurid, probably Tyrannosaurus Rex."

Reporting in the Cretaceous Research journal, they note the skull and skin of the large adult duckbill dinosaur dates to around 66 million years ago, around the end of the Age of Dinosaurs. The specimens were excavated in the Hell Creek region of Montana, renowned for past Tyrannosaurus and duckbill dinosaur discoveries. Duckbills were the cows of the dinosaur era, plant eaters often seen as prey for the carnivores of the time.

"Healing skin injuries appear to be rare in the fossil record for good reason – prey rarely escapes once the attacker latches onto it," the paleontologists say. In this case, the duckbill hide bears signs of numerous healed bites and even bone damage, marks resembling healing that takes at least three weeks in modern reptiles. The researchers call for more study of fossilized dinosaur skins to add to their findings, which may provide evidence for debate over whether T. Rex was more of a hunter or a scavenger.